Transformer.



. FORTESGUE G. LEG

Patented Feb. 23, 1915.

A TTORNEY WITNESSES UNITED STATES PATENT OFFICE.

CHARLES LE G. FO'RTESCUE, F PITTSBURGH, PENNSYLVANIA, ASSIGNOB T0 WEST- INGHOUSE ELECTRIC AND MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

TRAN SF ORMER.

' To all whom it may concern:

Be it known that I, CHARLES LE G. FOR- TESCUE, a subject of the King of England, and a resident of Pittsburgh, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Transformers, of which the following is a specification.

My invention relates to electric apparatus and it has special reference to such current or series transformers as are adapted for high-voltage service.

The object of my invention is to provide a transformer of the class above indicated which shall not only be capable of withstanding the strains incident to very high voltages but shall also be adapted for use in the open air or in localities where it is exposed to adverse weather conditions.

Series transformers have sometimes been constructed to comprise a hollow circular or rectangular core member about which lowpotential coils are wound, an insulating sleeve. or bushing extending through the opening and a high-ootential winding consisting of one or more turns of suitable" insulated cable or other conductor threaded through the sleeve or bushing.

In accordance with my present invention, I provide a transformer of the above-mentioned character with suitable means for adequately protecting the device from the weather so that it may be used in the open air without injury to the insulation which electrically separates the high-potential winding or conductor from the low-potential winding and the core member.

Figure 1 of the accompanying drawings is a sectional elevation and Fig. 2 is an end elevation of a transformer constructed in accordance with my invention. Fig. 3 is a view, corresponding to Fig. 1, and Fig. 4 is a plan view of a'modified form of transformer, which also embodies my invention. Fig. 5 is a partially sectional elevation of another modification in which a built-up insulator is substituted for the metal hood of Fi 1.

l teferring to Figs. 1 and 2 of the drawings, the structure here shown comprises a laminated annular core member 1, low-p0- tential coils 2 and 3 wound thereon, a metal sheath 4 which incloses the low-potential winding, an outer sheath or covering 5 of Specification of Letters Patent.

Patented Feb. 23, 1915.

Serial No. 642,874.

sheet metal, and molded insulating material 6 which separates the parts 4 and 5.

A metal tube 7 is secured to and extends downwardly from the metal sheath 4 and may form a part of it, the low-potential conducting leads 8 and 9 of the transformer being threaded through the tube. The outer sheath or covering 5 is provided with a flaring tubular projection constituting a hood 10 which is substantially concentric with the tube 7.

The hood 10 serves not only to carry the rain and moisture away from the terminals 8 and 9 but increases the insulating surface distance between the members 4 and 5', as indicated at 11 in Fig. 1. The sheet metal sheaths 4 and 5 both conform, in general, to the shape of the core member 1 and an opening 12 which is concentric with the opening in the 'annular core member 2. The opening 12 is provided in order that a high-potential conductor 13 which constitutes the primary winding may be threaded therethrough. The shape of the hood 10 is also such as to preclude a concentration of the lines of force of the static field existing between the supporting tube 7 and the hood, and the exposed surface of the insulating material 11 is of such a form as to conform in shape to these static lines of force. In order to subject the I dielectric material 6 to substantially uniform electrostatic stresses, the tubular member 7 and the shield 10 are so shaped as to produce substantially parallel static lines of force between them. To accomplish this, the shield 10 is flared outwardly a small degree, the rim of said shield beingremotely removed from the tubular member 7. By means of this construction, a concentration of the field upon certain points of the members 7 and 10 is substantially prevented and the said parts are more effectively insulated from each other than would otherwise be the case.

In order to prevent the sheet-metal members 4 and 5 from acting as short circuited secondary windings, they are provided with slots 14 and 15 near the center of the opening 12. It is evident that small openings at this point do not materially detract from the amount of protection afforded by-these parts. I

Referring to Figs. 3 and 4 0f the drawings, the structure here shown comprises an annular core member 16 corresponding to the member 1 of Figs. 1 and 2, a secondary winding 17, surrounding the core member and substantially inclosed by a casing 18 which corresponds to the sheath 1. An insulating tube 19 extends through the opening in the core members 16 and supports, near its ends, a substantially spherical shield 20, composed of a plurality of overlapping segments 21 which are insulated from each other.

A tube 22, which corresponds to the tube 7, extends downwardly from the casing 18 and through a hole 23 of relatively large diameter in the bottom of the shield 20.

It is evident that the shield completely protects the device from moisture and, at the same time, a high-potential conductor 24 may be threaded through the bushing 19 to constitute the primary winding of the transformer. The shield 20 may be omitted when the transformer is adapted for indoorv service.

The transformer shown in Fig.5, which is similar to that of Fig. 1, has an insulator 25'which is built up of a plurality of nesting parts 26 of porcelain or other similar material cemented together and interposed between the hood 10 and the tube 7. The

metal hood is much smaller when the insulator 25 is employed. By making the casings 4 and 18, which surround the secondary windings of the devices relatively heavy and rigid, the transformers may readily be supported by the tubular projections 7 and 22, provided these projections are made adequate. The devices, as a whole, then resemble very high-potential insulators and may be similarly mounted on the tops of poles or cross arms. When this is done, the outer metal coverings or sheaths 10 and 20 may be maintained at the high-voltage line potential and it is then unnecessary to uti lize any insulation on'the surface of the conductors l3 and 24 except such as is necessary to properly separate between turns.

Itis evident that modifications ma be effected in the structure illustrated wlthin the s irit and scope of my invention.

I c aim as my invention:

1. A transformer comprising an annular magnetizable core, a winding thereon, a metal sheath surrounding the winding and provided with a tubular projection through which the terminals of the winding extend, an outer metal sheath substantially concentric with the inner sheath, and interposed molded insulationbetween the two sheaths, the tubular projection of the outer sheath being flared outwardly to constitute a hood or water-shed.

2. An electrical device com netizable core, leads,

rising a maga winding tereon having a conducting casing surrounding the core and the winding and'having a hollow extension that surrounds the said leads and supports the device, a tubular conducting member extending through the core and the conducting casing, an insulating body that is interposed between the said casing and the said member and that insulates the conducting member from ,the aforesaid parts and from the ground, and a winding that passes through the conducting member and surrounds the core. I

3. An electrical device comprising a magnetizable core, a winding thereon having leads, a conducting casing surrounding the core and the winding and having a hollow extension that surrounds the leads and sup ports the device, a tubular conducting member extending through the core andthe conducting casing, a winding that passes through the conducting member and surrounds the core, and an insulating body that is interposed between the said casing and the said member and the exposed surfaces of which are shaped to substantially conform to the direction of the static lines of force extending between the adjacent por-I tions of the said casing and the said mem ber.

4. An electrical device netizable core, a winding thereon, a conducting casing surrounding the core and the winding, a tubular conducting member extending through the core and the conducting -casing, a' winding that passes through the conducting member and surrounds the core, and an insulating body that is interposed between the said casing and the said member and the exposed surfaces of which are shaped to substantially conform to the direction'of the static lines of force extending between. the adjacent portions of the said casing and the said member.

5. An electrical device comprising a magnetizable. core, awinding thereon, a conducting casing surrounding the core and the winding and having an extension that supports the device, a tubular conducting member extending through the core and the conducting easing, an insulating body that is interposedbetween the said casing andsurrounding the extension 0 the inner cas-v ing, an insulating body thatis interposed comprising a'magn w. 1 o s v a between the said casings and the exposed subscribed my name this 31st day of July, surfaces of which are shaped to substan- 1911. tially conform to the directlon of the statie lines of force extending between the said .ex- CHARLES LE FORTESCUE' s tensions, ancl' a winding that surrounds the Witnesses:

outer'casing. R. J, DEARBORN,

In testimony whereof, I have hereunto -B. B. Hume. 

